High Lockout
F9 on Glow-worm Xtramax HE

Your boiler has detected an issue with its internal sensor that monitors water pressure, preventing it from heating up.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Water pressure sensor fault.

What causes this fault?

This fault occurs when the boiler's control board loses communication with the sensor that monitors internal water pressure. The most common reason is that the sensor has developed an electrical failure or has become blocked with system debris, preventing it from sending a steady signal. In some cases, the issue is caused by loose or damaged wiring connecting the sensor to the main computer.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F22View →

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